Field of the Invention
The present invention relates to a method for making a toothbrush.
Description of Related Art
A toothbrush usually has a handle and a head. The head comprises at least one cleaning element extending therefrom. A cleaning element in the meaning of the present invention can be a single bristle, a bristle bundle, i.e,. a bristle tuft or an elastomeric cleaning element. Said cleaning element is projecting a first, i.e., front face of the head of the toothbrush for cooperating with the teeth to be cleaned in a conventional manner. The toothbrush generally comprises other cleaning elements including cleaning elements for cleansing soft tissue in the mouth, e.g., as known from U.S. Pat. No. 7,908,699 B2. Such cleansing elements are generally provided on the back face of the brush head, i.e., the face which is essentially parallel to the first face and opposite thereto. Such cleansing elements are usually provided for removal of microbial debris from the soft tissue, which soft tissue in particular is the tongue of the user of the toothbrush. In the course of the cleaning action, excessive pressure on the toothbrush and in particular the gums is to be avoided. Thus, it is generally known in the art of toothbrush making to provide a hinge between the handle and the head of the toothbrush. Thus, the head has the ability to flex in response to excessive forces between the at least one cleaning element and the teeth, in particular the gum surrounding said teeth.
It is known in the art to make the toothbrush with a base body of a first thermoplastic material, which usually is a hard component thermoplastic material. In order to provide the hinge, the base body can have a reduced thickness, i.e., cross-section in the area of the hinge and a geometry adopted to allow the head to flex relative to the handle. The constitution is such that flexing is in particular feasible about an axis extending perpendicular to the longitudinal extension of the toothbrush and essentially parallel to the first, i.e., front face of the brush head.
In order to avoid bacteria and dirt collecting in the area in which the base body has a reduced cross-section, the harder thermoplastic component of the base body is covered by a softer component, which usually is a thermoplastic component, in particular a thermoplastic elastomer. The softer thermoplastic component is usually applied by injection molding around the base body. Apart from covering the harder thermoplastic component in the area of the hinge, the softer thermoplastic component can likewise be provided for improving the haptic properties of the handle, e.g., as known from U.S. Pat. No. 7,047,591 B2.
In the generally known manufacturing process for making such toothbrush, the base body is generally made by injection molding a first, harder thermoplastic material into a first mold. After solidification, the base body is demolded and transferred to a second mold, which is slightly larger than the first mold, i.e., the mold for making the base body. The voids between the second mold and the base body are then filled by injection molding the softer thermoplastic component into the second mold to provide a thermoplastic covering and/or thermoplastic sleeves or coatings, cushion or the like by injection molding around the base body. Then, the toothbrush body is demolded. The toothbrush body can, for example, be injection molded around by at least one further component which can be a harder component or a softer component.
While the above manufacturing process is well adopted and used in the art, there is need for a further improvement of the known method. Thus, it is one object of the present invention to propose a method which is capable of allowing making a toothbrush, which toothbrush has a base body specifically adopted to cope with different needs to fulfill for making the handle on the one hand, and the head on the other hand, and to provide a method for making a toothbrush suitable to more economically manufacture the toothbrush.